|OPERATIONS of Psat IN THE AMATEUR SATELLITE SERVICE 26 July 2010
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| WB4APR
|
|This paper addresses the licensing of Psat in the Amateur Satellite
|Service. It extracts the pertinent sections of the IARU (International
|Amateur Radio Union) guildelines for INFORMATION FOR PROSPECTIVE OWNERS
|AND OPERATORS OF SATELLITES UTILIZING FREQUENCIES ALLOCATED TO THE
|AMATEUR-SATELLITE SERVICE which helps assure compliance with the ITU
|rules. This document may be viewed in its entirety at:
|http://www.iaru.org/satellite/prospective.html
|
|RULES:
| "Amateur-Satellite Service: A radiocommunication service using space
| stations on earth satellites for the same purposes as those of the
| amateur service." [RR S1.57]
|
| "Amateur Service: A radiocommunication service for the purpose of
| self-training, intercommunication and technical investigations
| carried out by amateurs, that is, by duly authorised persons
| interested in radio technique solely with a personal aim and without
| pecuniary interest." [RR S1.56]
|
|Psat COMMENT:
|
|Sponsoring Organization: US Naval Academy
|Operating Organization: US Naval Academy Amateur Radio Club W3ADO
|Station Trustee: Bob Bruninga, WB4APR
|Satellite Station Licensee: Ryan Johnson, K3FOR
|
|Bob Bruninga is the senior research engineer in the Naval Academy
|Student project lab who gives engineering guidance to student
|satellite projects.
|
|Ryan (Skip) Johnson is an active friend of the Academy, a past
|president and Officer Representative of the Amateur Radio Club, who
|still meets with it regularly. He is an unpaid Naval Reservest with
|NO PECUNIARY association with the US Naval Academy, NRL, NASA nor
|any other Organization involved in this project.
|
|RULES:
|
| "VI. OPERATIONAL GUIDELINES. The following operational guidelines,
| based on interpretations by IARU of the Radio Regulations and good
| amateur practice, are intended to help in planning the missions,
| management, and control of satellites planned to operate in the
| amateur-satellite service.
|
| Organisations building satellites should compare their mission
| plans to the requirements of the amateur-satellite service. Then,
| they should determine if it is possible to comply with the
| requirements of the amateur-satellite service or if licensing and
| operation should be in some other radio service which is more
| consistent with the nature and requirements of the mission.
|
|RULE: A. Positive Transmitter Control.
|
| You must be able to turn off the space station transmitter
| immediately in case of interference. [RR25.11 & RR 22.1]
|
| In practice the meaning of "immediate" probably varies a little,
| depending on the situation. If interference is caused to a SAFETY
| SERVICE, immediately means NOW: no more than minutes or a few
| tens of minutes. Interference to other services should be terminate
| in no more than a few hours.
|
| Positive transmitter turn-off signals shouild use an independent
| telecommand receiver on the space station. Telecommand on a user
| input frequency means that another transmitter can interfere easily
| with your telecommand signalso so as to obstrut control.
|
| An adequate network of well placed earth statinos capable of
| sending control signals to the satellite reduces the time required
| to issue the turn off command. Other mechanisms might be (1) a
| transmitter time-out timer independent of the houskeeping or
| control computer; or (2) limiting the space statio's power budget
| so that it will run out of energy and sop operating in a reasonably
| short time.
|
|Psat Comment: Psat's packet transmitter operates in a time-division
|multiplex environment where it operates in a low-TX-duty-cycle
|mode, designed to share the channel with users, and other satelites
|and systems. Psat's transmitter can be shut down within the
|requirement of this rule:
|
|1) Psat has an independent packet-length watch dog timer that limits
|packet length to 1.5 seconds maximum.
|
|2) Psat's Comm control system has a watchdog timer on the comm
|system that detects loss of control once a minute and re-boots the
|comm processor which would also reset any stuck transmitter.
|
|3) Psat's command and control processor also has a watchdog timer
|that reboots the command and control system to defaults if the
|process or locks up.
|
|4) Psat's 4 watt transmitter power (8 watts DC input) exceeds the
|spacecraft's power budget by a factor of 5 or more, and will
|deplete the system power in under an hour of stuck transmitter.
|
|5) Psat uses FM for the command link, and so even in the presence
|of a jamming signal, a command signal only 10 dB stronger than
|the jammer is needed to execute the transmitter off command. This
|10 dB command ratio is easily assured:
|
| a) Through the use of multiple ground command stations through
| out the world separated in time by 10's of minutes in different
| footprints that can avoid any single jammer.
|
| b) The geometry of any single pass over a command station and
| jammer varries by at least 6 to 8 dB simply due to the range
| equation, plus 4 to 8 dB due to the variation in antenna
| pattern. Combined, these allow a variation between 10 to 32 dB
| between the jammer and the command station, giving assurance
| that the one-second shut-down command can be received.
|
|RULE: B. The purposes of an amateur satellite should be to:
|
| (1) Provide communication resources for the general amateur
| radio community and/or
| (2) Self training and technical investigations relating to
| raido technique. [See RR S1.56 and RR S1.57.]
|
| "Radio technique," means having a reasonable possibility of
| application to radio communication systems. [RR S1.56 and
| RR 11.57 and RR 25.2]
|
| Examples relating to radio technique include but are not limited
| to communiction protocols, attitude determination methods, command
| and control procedures, receivers, transmitters, and transponders.
| Also antennas, sensors to study spacecraft performance, telemetry
| protocols, power supplies and controls for use in space. In
| addition, spacecraft computers, memory operating systems, programs
| and related items; radiation effects on electronic components;
| radio wave propogation, meteor trail reflection, and measurements
| of orbital environment.
|
| While many other types of technical investigations are conceivable,
| those not having a reasonable possibility of application to radio
| communication systems are probably not in accordance with the
| treaty requirements. An administration can reject whatever it
| decides is inappropriate use of the amateur-satellite service or
| questions may be raised by other administrations.
|
|Psat COMMENT: Psat is fully in compliance with the purposes above.
|
|1) The Psat communication system is designed as a two-way trans-
|ponder in support of amateur radio communications, particularly remote
|data relay, text messaging, and situational awareness.
|
|2) The auxilliary communications transponder operates as a two-way
|PSK-31 transponder in full support of amateur users.
|
|3) The extremely low-cost solar panels on Psat provide space
|heritage for other small amateur satellite builders.
|
|RULES: C. Station Control. Who may operate a transmitter
|
| All stations operating in the amateur service and the amateur-
| satellite service, including space and Earth stations, must be
| controlled by "duly authorised persons," that is, individual
| licensed amateur radio operators who must be acting "solely with
| a personal aim and without pecuniary interest." [S1.56 & S1.57.]
|
| Even with these limitations, organisations and amateurs have
| common interests and work together for their mutual benefit.
| (For this discussion, an organisation can be a university,
| research institute, for-profit or not-for-profit corporation,
| association, club, or other similar entity.)
|
| AMSAT-NA, for example, is an organisation which owns and builds
| space stations to operate in the amateur-satellite service. But,
| because it is an organisation and not an individually licensed
| radio amateur, it may not control an amateur station. Licenses
| under which AMSAT-NA owned amateur stations are operated may be
| issued in the name of an individually licensed amateur radio
| operator. They may also be issued in th ename of an amateur radio
| club (in this case, AMSAT-NA itself) where a licensed amateur
| radio operator is named on the license as trustee (the person
| responsible) for the club station.
|
| In every case, one individual, a licensed amateur radio operator,
| who is neither employed nor paid by AMSAT-NA, is legally
| responsible for the operation of each amateur station or amateur-
| satellite station.
|
| Commonly, the licensee is an unpaid member of the organisation
| owning the amateur station equipment or is a volunteer acting
| in close association with it. In these cases, the owner's interest
| and the licensee's "personal interest" are usually the same.
|
| Of course, it is theoretically possible (although to the best of
| our knowledge, it has never occurred in practice) that the
| licensee or trustee of an amateur station or amateur-satellite
| station may determine that something he or she has been requested
| to do is not in accordance with the rules and regulations of the
| licensing administration. If this happens, the licensee would
| inform the organisation and, if possible, they would work out a
| solution that satisfies and protects both.
|
| Thus, the individual responsibility of each licensed amateur
| radio operator, imposed by the Radio Regulations, works as a
| legal safety check for the organisation and the amateur to
| protect both of their interests and those of the amateur
| satellite service as well.
|
|Psat COMMENT: Psat's organizational structure and operators are
|compliant with these rules. The operating organization is the school's
|Amateur Radio Club with WB4APR as the licensed trustee of the station
|and the licensed control operator for the satellite will be Skip Johnson,
|K3FOR as noted above. The interest of these individuals is in the
|operation of the satellite for personal training and intercommunications
|with other satellite experimenters in the amateur satellite service and
|without pecuniary remuneration for such interest. Bob Bruninga has a 20
|year non-pecuniary history with the Amateur Satellite Service, the author
|of dozens of related papers in AMSAT and other Amateur Radio publications,
|and the instigator of Packet Radio APRS position reporting via SAREX, MIR,
|ARISS, SUNSAT, SAPPHIRE, PCSAT1 and 2, ANDE and RAFT for purely personal
|aims of promoting the Amateur Satellite Service.
|
|
|RULE: E. Permissible communications:
| The amateur-satellite service, by its nature, involves stations of
| more than one country. Transmissions between amateur stations of
| different countries must be limited to communications consistent with
| the purpose of the amateur service [RR 1.56] and to remarks of a
| personal character [RR25.2].
|
| Transmissions between amateur stations on different conutries may not
| be obscured. THis means that (1) technical descriptions of all
| emissions, codes, and formats must be made publicly and widely
| available and that (2) technical descriptions must be sufficient to
| enable any technically competent licensed amateur radio operator to
| use the system. You may do nothing intended to conceal the meaning
| of a tranmission, except in the case of space telecommand
| transmissions for critical spaeccraft functions [RR 25.2A]
|
|Psat COMMENT: The design, telemetry, data and all aspects of Psat are
|in plain language (AX.25 protocol) and all details are published and
|maintained current on the following WEB page:
|http://www.aprs.org/Psat.html
|
|RULE: F. Open Access.
| All telecommunication facilities, except telecommand, operating in amateur-satellite service allocations should be open for use
| by amateur radio operators world-wide. All experiments utilising
| frequencies allocated to the amateur-satellite service should be freely
| available for use by radio amateurs world-wide and incidentally for
| reception by students and educators.
|
|Psat COMMENT: All communications modes except telecommand and all
|telemetry will be available to all amateur radio operators worldwide in
|accordance with the published user operating recommendations. There is
|no other usage of these communications transponders, nor circuits beyond
|what has been described here for use in the Amateur Satellite Service.
|Psat's transponders are available to radio amateurs worldwide who adhere
|to the published recommended user station requirements and uplink
|parameters.
|
|Bob Bruninga, WB4APR
|Trustee,
|US Naval Academy Amateur Radio Club
|410-293-6417